Mika married into the Yamaguchi family as his second wife. Perhaps because it hasn't even been a month since they started living together, Mika and Tetsuya, the son of a ronin, have a somewhat aloof relationship. One day, Tetsuya looks into the sex of his father and mother-in-law. A gentle face during the day and a nasty face at night. From that day on, Tetsuya's head becomes full of thoughts about Mika. Lewd delusions with his mother-in-law spring out one after another, and Tetsuya finally reaches the limit of patience.